Center break disconnect switch contacts



M y 1955 w. H. GlLLlLAND ETAL CENTER BREAK DISCONNECT swncu CONTACTS Filed Feb. 27, 1952 2 Sheets-Sheet l INVENTORS WILLIAM H. G'ILLILAND FITZHUGH H. TURNHAM BY www ATTORNEYS May 31, 1955 w. H. GILLILAND ETAL- 0 CENTER BREAK DISCONNECT SWITCH'CONTACTS Filed Feb. 27, 1952 2 SheetsSheet 2 INVENTORS WILLIAM H. G'ILLILAND FlT'ZHUG-H H.. TURNHAM ATTORNEYS United States Patent CENTER BREAK"D1SGNNECT SWITCH CONTACTS William H. Gilliland and Fitzhugh H. Turnliam, Birmingham, Ala assignors to Usco Power Equipment Corporation, 15irmingham,.Ala.,. a. corporation of Alabama Application February 27 1952, Serial No. 273,654

'7 (Claims. (Cl. 200-170) This invention relates toelectric switches and more particularly to center break switches of the type commonly used on high tension. transmission lines.

For the eflicient operation of such switches, highpressure engagement between the cooperatingcontact members is necessary when the switch is closed and yet easy and quick opening movement of said contact members must be provided. Numerous: constructions have been heretofore proposed which have usually lacked oneor theother of the above attributes. They employ-a number of contact fingers of the springor pivoted type which are of comparatively delicate-construction: and liableto breakage, especially should be contact carrying arms become slightly misaligned. crease production costs and embody multiple'wearingsurfaces so that the coacting parts eventually losethe required high pressure engagement.

Accordingly, it is one oftheprincipal objects of this invention to provide a center break switch having. novel coacting contact elements of very rugged construction and embodying means insuring high pressure engagement of said contacts in circuit closing position while permit ting of easy and quick movementof: the contacts to open and closed position with application of a minimum of manual force.

Another object resides in the provision of simple onepiece contact elements one of which is resiliently urged at spaced points into pressure engagement with: the other contact.

A further object resides in providing switch contacts with adjustable means for. regulatingthe pressure force to maintain a good electrical connection between the contact members in circuit closing position which also compensates for wear of the contacting surfaces of said members.

It is an additional object of. the invention. to provide novel means mounting said adjustable means and the re siliently yieldable contactmemberonone' of the swingable arms of the switch assembly to aiford protection against accumulations of snow and ice which might impair the efficient and reliable operation of the switch.

It is also an important object of the: invention to provide a novel mounting and arrangement of one contact member with respect to the axis of the switch arm-by which it is carried and the cooperating contact member. carried by .the other switch arm, whereby engagement and disengagement of said contacts will be greatly facilitated and wear thereof reduced to a minimum.

With the above and other objects'in view the invention comprises the improved electrical switch as herein characterized and the construction and relative arrangement of its several parts, as will be hereinafter more fully described, illustrated in the accompanying drawings and subsequently incorporated in the subjoined claims.

in the drawings, wherein several simple and practical embodiments of the invention are shown and in which similar reference characters designate corresponding, parts throughout the various views:

Also suclr constructions considerably in-- ice Figure 1 is a side elevationalview showing a more or less conventional center break switch assembly for high tension transmission lines including a preferred embodiment of the present invention;

Figure 2 is a plan view, partly in section, on. an enlarged scale, of the contact members in circuit closing engagement, and showing the normal. condition of the resilient contact member in dotted lines;

Figure 3 is a side elevational view of the contact members of Figure 2;

Figures 4 and 5 are side elevation and plan views respectively of the modified'contact member; and

Figures 6, 7 and 8 are semi-diagrammatic plan. views illustrating various relative positions of the coacting contact members in their movement towardcircuit closing-position, and showing a slightly modified. form. of one: of said members.

Referring in further detail to the drawings, theswitch assembly is mounted upon a suitable supporting base 10 and includes two spaced insulator units or stacks 12 and 14 respectively. In the present instance we have shown three rigidly connected units in each stack provided with coaxial spindle extensions 16 and 18 respectively, at theirlower ends which are supported and rotatably journalled in suitable bearings 20 and 22 on the base 10 in. any well known conventional manner.

Upon the upper ends of insulator stacks 12 and 14, terminal members 24 and 26 respectively are. secured to which flexible conductors28 and 30 are connected. Arms 32 and 34 of copper tubing are respectively rigidly fixed at one of their ends to the terminal members 24 and 26 and extend radially therefrom in a common plane. These arms are preferably provided with suitable arcing horns 36 and 38 respectively.

Suitably located radial arms 39 are respectively fixed to the spindles 16 and 1S and connected to the ends of 1 rod 40 so that the two stack insulators 12 and 14 will: be rotated in unison in relatively opposite directions. Manually operable actuating means (not shown) for the insulators may be connected in usual manner to either spindle 16 or 19 and suitable stop means 41 is provided to limit rotation of the insulators in each direction.

As thus far described, the switch assembly follows standard practice in the art and, it will be understood as this description proceeds, that our novel improvements may be advantageously used in connection with other conventional types of switches.

Referring now more particularly to Figures 2 and. 3 of the drawings, a male contact member 42 is provided in the form of a loop of electrically conductive metal of substantial width closed at one end by a split sleeve 44 rigidly secured upon the free end of arm 32 by a clamping bolt 46 and nut 47. At its other end, the side arms of the loop 42 are integrally connected by a contact blade 48 of somewhat greater width than side arms and having opposite protuberant rounded or convex edge surfaces 50. In this embodiment of the invention the blade 48 lies in a plane substantially normal to the axis of the arm 32 and the side arms are reinforced throughout the length by axially extending ribs 51.

A forked bracket having spaced: parallel arms 52 integrally connected at one end by a splitv sleeve 54 is securely fixed upon the free end of arm 34 by a clamping bolt 55 and nut 57. The female contact member 58, formed from two lengths of electrically conductive metal of uniform width bent into elongated U form to provide spaced pairs of yieldable contact arms and 62 connected by semi-circular intermediate portions 64, are disposed within the forked bracket. To this end, the bracket is provided with a curved seating face 66 for portions 64 of the contact members which are securely fixed thereto by clamping members 68 and spaced cap screws 70. The pairs of contact arms 60 and 62 lie in opposed relation to the inner sides of the respective bracket arms 52. The bracket and contact arms are disposed relative to the axis of arm 34 in 90 angular relation to the position of the opposite sides or" the loop 42 of the male contact member with respect to the axis of arm 32. The free end of each contact arm 6% and 62 is outwardly curved on a large radius as at 72 to dispose the ends thereof in overlying relation to backing lip 74 formed on the end of the adjacent bracket arm 52. These curved ends of the contact arms serve to guide the contact blade into the space between the contact arms and also serve as stops for limiting the approaching movement of arms 60 and 62 when the switch is open by engaging lips 74 as shown in dot dash lines in Figure 2.

Each bracket arm 52 has an integrally formed cylindrical housing structure 78 at its outer end. Each housing contains a coiled spring 80 and a follower 82 seated against one end of the spring by an adjusting screw 84 threaded in the outer end wall of the housing and provided with a lock nut 86. The spring 80 at its other end surrounds a centering boss 88 on a disk or plate 90 held in pressure contact with the outer face of the adjacent yieldable arm of contact member 53 by said spring. It will be evident that by adjustment of the screws 84 the resistance of springs 8%) to a relative separating movement of the opposed contact arms 6i) and 62 from normal open-circuit position, shown in dot dash lines in Figure 2, may be variably regulated without varying the normal open-circuit position determined by engagement of curved contact ends 72 with lips 74.

From the above description, it will be seen that as the insulators 12 and 14 are rotated in opposite directions, the arms 32 and 34 are swung horizontally toward each other. As they approach an axially aligned position contact blade 48 enters betewen the curved ends 72 of the pairs of arms 69 and 62 of the contact member 58 forcing said arms apart as the convex edges 50 of blade 48 move inwardly on the opposed surfaces of said arms to provide line contact between the respective arms 60 and 62 and blade 48 when the position shown in Figure 2 is reached. Springs 80 are thus placed under compression to exert an inward pressure force on contact arms 60 and 62 to produce a very high pressure engagement between the coacting part of the male and female contact members Owing to this high pressure engagement and the rugged construction of the contact members they are capable of carrying a heavy current without becoming excessively heated or by-passing current through springs 80 and tempering the springs and varying the engaging pressure in use. Overheating is also further avoided by reason of the fact that air may freely circulate through the loop 42 and between the bracket arms 52 in intimate contact with the surfaces of the contact members.

The line contact between the edges 56 of blade 58 and contact arms 6% and 62 minimizes the area of any cerrosive or ice seal which may form between the contact members, thereby insuring quick opening operation of the switch without appreciable restraint of the relative swinging movement of arms 32 and 34. The opening and closing movement of the switch arms is also facilitated by reason of the fact that contact arms 6% and 62 locally yield to pressure contact with the blade 43 in the engagement and disengagement of the contact members. While two independent contact strips form contact member 58 in the drawings, it will be appreciated that a one-piece U-shaped member having slotted free ends may be substituted therefor without departing from the present invention.

As seen in Figure 3, the length of blade 48 is greater than the combined width of contact arms 64) and 62. Thus relative displacement of switch arms 32 and 34 out of horizontal alignment, which may be caused by atmospheric conditions or incidental wear in the bearings of insulators 12 and 14, will not impair the eflicient and reliable operation of the switch. Wear of the corn tact surfaces of blade 48 and arms and 62 may be readily compensated by properly regulating the pressure applied to said arms by springs 80 through the adjustign screws 84.

In Figures 4 to 8 of the drawings, there is shown a slightly modified form of the invention which difiers from that above described only in the angular position of the contact blade with respect to the axis of switch arm 32. As most clearly shown in Figure 4, the contact blade 48 is disposed in an obliquely inclined plane relative to the axis of arm 32. This structure results in appreciably less resistance to the closing operation of the switch and reduced wear of the contact members with a quicker break between said members in the opening operation.

In Figures 6, 7 and 8 the centerline of the switch assembly which intersects the axes of the insulators 12 and 14 is represented by the line C. When the switch arms 32 and 34, in the closing operation, reach approximately the relative positions seen in Figure 6 the blade 48 has cleared the end of arm 62 and is positioned between the contact arms though out of contact therewith. At the time the switch arms arrive at the position of Figure 7, substantially parallel to centerline C, the opposite edges of blade 48 first contact the pairs of arms 60 and 62 of contact member 58. The limiting stops for insulators 12 and 14 are so set that the switch is not fully closed until the switch arms are disposed at the other side of the centerline C in substantially the relative positions of Figure 8. In this latter movement of the switch arms, blade 48 spreads or separates the pairs of contact arms 60 and 62 and is positioned in a plane substantially normal to the axis of switch arm 34. It will be noted that in the movement of the contact members between the positions of Figures 7 and 8, the relative linear movement between their engaged surfaces is very short, thus reducing wear of said surfaces to a minimum.

This arrangement of the contact blade 48' provides greater ease of operation of this type of switch with less manual exertion. Also in the opening of the switch a quick break or separation of the contact members is obtained, resulting in rapid attenuation of the arc and its early extinguishment.

From the foregoing, the construction, manner of operation and several advantages of the described embodiments of the invention will be readily understood. It will be appreciated that there is provided an electrical connector or switch mechanism for high tension power transmission lines in which the several parts are of exceedingly rugged and durable construction to withstand the abusive handling to which such switches are frequently subjected in the field. At the same time, the invention provides novel means insuring the desirable high pressure engagement of the coacting contact members when the switch is closed while permitting easy and quick operation of the switch to its open and closed positions. It will, of course, be apparent that circuit making and breaking contacts embodying the essential characteristics of the present invention may also be functionally adapted for use in connection with various other types of switch mechanisms.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. In a center break disconnect switch assembly having spaced rotatable insulators and a respective switch arm rigidly connected at one end to each insulator adapting their respective free ends for swinging movement into and out of circuit closing relation: a rigid male contact blade connected with the free end of one switch arm; a resilient female contact assembly comprising a rigid forked bracket secured to the free end of the other switch arm and providing laterally spaced arms, at least one pair of opposed, substantially parallel, laterally yieldable arms mounted in said bracket between said arms and movable with respect to said bracket whereby said yieldable arms may be forced apart by said blade in the closing operation of said switch; means electrically connecting said yieldable arms at their adjacent inner ends in parallel in said switch circuit whereby the passage of current therethrough establishes a magnetic force efiective to urge said yieldable arms into pressure engagement with said blade; resilient means coacting with said yieldable arms and the respective spaced bracket arms to resiliently augment said magnetic force and further urge said yieldable arms into pressure engagement with said blade; and stop means on said bracket to establish a normal open-circuit position of said yieldable arms.

2. Switch structure as defined in claim 1, wherein said yieldable arms constitute portions of a one-piece member of elongated U form having its intermediate portion only fixed to said forked bracket.

3. Switch structure as defined in claim 1, wherein said contact blade is disposed in an obliquely inclined plane relative to the axis of its switch arm.

4. Switch structure as defined in claim 1 wherein each bracket arm is provided with a housing structure and said resilient means comprises a coiled spring in each housing and adjustable means regulating the pressure applied by said spring to the yieldable arms.

5. A contact assembly for a high tension electrical switch comprising a transversely split mounting sleeve adapted to receive a clamp bolt and nut assembly and having a forked arm portion extending from one end, the connecting portion of said forked arm being provided with an arcuate seat; at least one substantially U-shaped contact strip having a bridge portion engaging said seat and contact arms normally in parallel spaced relation to the forked arms and to each other and arranged in parallel in said switch circuit whereby the passage of current therethrough establishes a magnetic force effective to urge said contact strips inwardly toward each other; arcuate clamp plates disposed between the contact arms in engagement with the other face of said bridge portion; and cap screws passing through said clamp plate and said bridge portions and threaded into said seat to removably secure said contact strip to said forked arm; resilient means interposed between the respective contact arms and fork arms to augment said magnetic force and resiliently bias the contact arms inwardly toward each other, and a clamp bolt and nut assembly operatively mounted in said sleeve for clampingly engaging said sleeve on the end of a movable contact supporting element.

6. The contact assembly of claim 5 wherein the free ends of the arms of the contact strips are curved outwardly on a large radius to guide a mating contact blade into the space between the contact arms in event of slight misalignment of the contact elements in use.

7. A contact assembly as defined in claim 1 wherein said contact portions at their free ends are each provided with a terminal portion return bent outwardly to overlie said bracket arms and said stop means comprises terminal lips extending from said bracket arms and positioned to respectively engage said terminal portions of said contact portions.

References (lited in the file of this patent UNITED STATES PATENTS 1,949,018 Koppitz Feb. 27, 1934 1,949,019 Koppitz Feb. 27, 1934 1,965,272 Wilkins July 3, 1934 1,976,006 Crabbs Oct. 9, 1934 2,306,117 Dunlap Dec. 22, 1942 2,510,051 De Montmollin et al. June 6, 1950 2,531,165 Scheuermeyer Nov. 21, 1950 2,553,892 Brugger May 22, 1951 

